fact optimal module of factsage to the optimization of sio ... · the main source of secondary lead...
TRANSCRIPT
Liquidus projection in the Al2O3-CaO-FeO-PbO-SiO2 quinary system. the isotherms are plotted for the regions
within the operational temperature range
Introduction
0
1
2
3
4
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6
7
1970 1976 1982 1988 1994 2000 2006 2012
Am
ou
nt
of
Pb
, m
illi
on
to
nn
es
Year
Primary production
Secondary production
Primary (ore extraction) and secondary (recycling)
lead production ratesReference: www.ilzsg.org
55.0%26.0%
3.5%10.5%
5.0% Paste
Grids, poles
Plastic residue
Acid
Polypropylene
The main components of acid batteries
Reference: G. Martin, “Recycling of used lead-acid batteries and
recovery of the polypropylene content,” World Metall. – Erzmet.,
vol. 61, pp. 243-247, 2008
Reference: www.ilzsg.org
The fields of lead application
80.0%
1.0%6.0%
3.0%
2.0%
5.0%
3.0%
Batteries
Cable Sheathing
Rolled and Extruded
ProductsShot/Ammunition
Alloys
Pigments and other
CompoundsMiscellaneous
The share of recycled lead in its total production increases with
time because of its economic and environmental benefits
The main source of secondary lead is spent acid batteries which
contain lead in amounts, sufficient for effective recycling
Nowadays, spent acid batteries are recycled almost completely.
Both metallic (grids and electrode plates) and paste (PbSO4 +
some amount of PbOx) are used for lead extraction
Sulfate paste is transformed into lead carbonate (cerussite)
which undergoes reduction with carbon in a furnace
Reference: www.recobat.comReference: www.recobat.comReference: www.recobat.com
Obtained results
Objectives and calculation tools
Fact Optimal module of FactSage software is
a perspective and powerful tool of process
optimization, which allows to perform a
minimization procedure in multicomponent
systems using various constraints on the
system and components properties
At a given SiO2 content, the optimal liquidus
temperature was searched with the constraint
PbO(slag)≤40 wt%;
At each obtained temperature and
composition the slag viscosity was calculated
using Viscosity module
The operational temperature must not exceed ≈ 1100°C (the lower limit is ≈ 500°C)
Slag viscosity should be as low as possible
Lead losses with off-gases should be minimized as well
Although it is possible to minimize two properties simultaneously in Fact Optimal, the
current version does not allow to perform viscosity optimizations directly; it is assumed
that SiO2 makes the major contribution to the slag viscosity
Pb losses with off-gas can be assumed proportional to Amountoff-gas*PPb species. Both
factors grow with T, therefore the minimization of Pb losses is equivalent to the
minimization of the operational temperature0.1
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0.10.20.30.40.50.60.70.80.9
0.1
0.2
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0.4
0.5
0.6
0.7
0.8
0.9
SiO2
PbO CaOmole fraction
Liq
Liq + C2S
Liq + C2S + Mono
Liq + Mono
Liq + CS
Liq + C2S + CS
C2S +
CS
C2S + C3S2
C2S
+ C
S +
C3S
2
Liq
+ C
S +
S
Liq + S
log(visc) = 3
log(visc) = 2
log(visc) = 1log(visc) = 0
log(visc) = -1log(visc) = -2log(v
isc) =
-3
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0.10.20.30.40.50.60.70.80.9
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0.4
0.5
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0.8
0.9
SiO2
PbO FeOmole fraction
Liq
Liq
+ F
aya
lite
Liq +SiO2
Liq + Mono
log(visc) = -3
log(visc) = -2
log(visc) = -1
log(visc) = 0
log(visc) = 1log(visc) = 2
log(visc) = 3
-10
-5
0
5
10
15
20
25
30
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
lg(η
, P
ois
e)
molar SiO2/(SiO2+MOx)
CaO-SiO₂ MELTS viscosity database
PbO-SiO₂ MELTS viscosity database
FeO-SiO₂ MELTS viscosity database
FeO₁˳₅-SiO₂MELTS viscosity database
AlO₁˳₅-SiO₂MELTS viscosity database
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0.10.20.30.40.50.60.70.80.9
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0.8
0.9
SiO2
PbO Al2O3mole fraction
Liq
Liq + PA6
Liq + Mull
Liq + S(s4)
Liq + Mull + S(s4)
Liq + A + PA6
Liq + Mull + A
Liq + A
log(visc
) = 3
log(visc
) = 2
log(visc
) = 1
log(v
isc
) = 0
log(v
isc
) = -1
log
(vis
c) =
-2
log(v
isc
) = -3
SiO2 - PbO - Al2O3
1200oC, 1 atm
T = 1200°C
Isoviscosity lines in the ternary systems including both silica and PbO
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
18.0
20.0
1020 1040 1060 1080 1100 1120 1140
Vis
cosi
ty,
Pois
e
Process temperature, C
min + 10 C
min + 20 C
min + 30 C
T(liq) + 10 C
T(liq) + 20 C
T(liq) + 30 C
Pareto front in the system CaO-FeO-Fe2O3-PbO-SiO2
2.0%
3.0%
4.0%
5.0%
6.0%
7.0%
24.0% 26.0% 28.0% 30.0% 32.0% 34.0% 36.0%
rela
tiv
e le
ad
loss
, %
wt% SiO2
T(liq) + 10 C
T(liq) + 20 C
T(liq) + 30 C
Lead losses in the system CaO-FeO-Fe2O3-PbO-SiO2
The optimization results in the system Al2O3-CaO-FeO-Fe2O3-PbO-SiO2 have shown that Al2O3
addition strongly increases slag viscosity and overall results are not substantially superior to
those without Al2O3
86.0
88.0
90.0
92.0
94.0
96.0
98.0
100.0
1020 1040 1060 1080 1100 1120 1140
carb
on
co
nsu
mp
rio
n,
kg
/to
nn
e o
f P
b
Process temperature, C
Carbon consumption per ton of lead produced
Results window of Fact Optimal module
Application of Fact Optimal module of FactSage to the optimization of
the lead recycling processEvgenii Nekhoroshev1, Sergei Decterov1
1Center for Research in Computational Thermochemistry (CRCT), Dép. de Génie Chimique, Ecole Polytechnique de Montréal, Montreal, QC, Canada